I upgraded from 8GB RAM to 24GB (G.SKILL RIPJAWS X Series), but Windows and CPU-Z shows that I only have 16GB installed?

[Pumpkin2999]

Just last night, I upgraded from 8GB to 24GB RAM in my gaming computer. As the title states, both Windows and CPU-Z are showing that I have only 16GB installed.

Just in case you need my specs, my motherboard is a Gigabyte GA-Z97-D3H.
The RAM I already had was G.SKILL RIPJAWS X Series (2x4 2133mhz).
My OS is Windows 8.1 (64-bit), and I don't believe I'm exceeding the RAM limit there.
I can provide more information if it's needed. Thank you!

 

[kanewolf]

Did you check the user's manual to see if there is a precedence required (larger DIMMs in specific slots)?

 

[Tradesman1]

What's the model #s of both old and new DRAM? What CPU and mobo? We've seen many buy a 2x set of DRAM marked as 8GB and thought each stick was 8GB where the 8GB designates the total of the package (2x4GB)

 

[Leaps-from-Shadows]

CPU-Z has an SPD tab. What does it say the new modules are?